Motor-vehicle.



E. GRUENFELDT.

MOTOR 'VEHICLE.

APPLICATION FILED MAR. 17. I913- 7, Patenteday 18, 191 5.

4 suns-shin 1.

E. GRUENFELDT.

MOTOR VEHICLE.

APPLICATION FILED MAR. 17. 1913.

4 SHEETS-SHEET 2,

' Patented May 18, 1915 51 woewtoz E. GRUENFELDT.

MOTOR VEHICLE. APPLICATION FILED MAR-17, 9]3- Patented May 18, 1915. v

4 SHEETS-SHEET 3- E. GRUENFELDT.

MOTOR VEHICLE.

APPLICAHON man MAR. I7, 1913.

Patented May 18, 1915.

4 SHEETS-SHEET 4- awwe wtoz to swing a vmotor vehicle in such manner as to EMIL GRUENFELDT, OI CLEVELAND, OHIO, ASSIGNOB TO THE BAKER MOTOE.VEHIOLE COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

I MOTOR-VEHICLE.

specification of Letters retent. Patented May 1915.

- Application filed Karol: 17, 1913. erle1No.7l54,982.

To all whom it may concern:

Be it known that I, EMIL GRUENFELDT, a subject of the Emperor of Germany, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certam new'and useful Improvements in and Relating to Motor-Vehicles, of which the following is a specification.

his invention relates to improvements in motor vehicles, more particularly motor vehicles in which an electric motor is employed for translating power for propelling the vehicles. One of the objects of my invention is to support an electric motor from the frame of rmit the motor during the normal operation of the vehicle, to readily and freelyaccommodate itself to any position into which the movements of therear drive axle may tend it relatively to the frame.

' Anot er object of my invention is-to em- I ploy a relatively high speed motor and at the same time support it from the vehicle frame so as to permit the floor boards of the vehicle body to be'disposed relatively close to the ground to provide a comparatively low hung chassis, as an entirety, the

necessary speed gear reduction between the armature shaft and the rear axle mechanism being arranged and disposed to accommodate such suspension of the motor inan' eficient and practical manner. I

Other objects of my invention will be readily appreciated by one skilled in this art from the description of one form of motor vehicle embodying it which for the purpose of illustration, i have, in the accompanying drawings, shown and hereinafter described.

Figure 1 is-a top plan view of a motor vehicle chassis, the bodytherefor not being shown. parts shown in Fig.1. Fig. 3 is a view of the rear axle mec anism and transmission gear casings, partly in plan and partly in section. Fig. 4 is a section through the differential gear and the driven connections between it and the lriven shaft, on the line 44 of Fig. 3. Figs. 5 and 6are sections on the lines 5'5 and 6--6, respectively of Fig. 4. Fig. 7 is a fragmentary view, partly in section and partlv 1n elevation,-of the motor and motor case, the propeller shaft, the'pro- Fig. 2 is a side elevation of the and associatedparts. Fig. 8 is an elevation of the gear casing. Fi 9 is a rear end view of the gear casing. Figs. 10, 11 and 12 are detail views of the universal 'oint,and Fig. 13 is a detail of the chain and sprocket.

In the drawings, 1 illustrates a suitable frame. It may be formed largely of channel iron or steel 1n the well known manner, or otheirwise constructed for its purpose as de-. sire Atits front end this frame is preferably supported by'an axle 2, steering wheels 3, and springs 4,1111 of WhlCh parts may be of any desired construction. Likewise the steering mechanism illustrated in the drawings '9 at its front-end is preferabl rigidly secured to the ball member 10' o a universal joint 10, the cup element 10 of which joint is rigidly secured to a cross bar 11 '-on the frame 1. This universal joint is. arranged in alinement, as shown, with the armature shaft 9 of the motor, its construction and disposition being such as to permit the motor to swing in substantially a l directionsand also to turn or. oscillate about theaxis of its armature shaft. The motor 9 is preferably of the type now commonly known as a high s eed motor, one, in other words, in which by its armature shaft in the normal operation of the motor in an electric motor vehicle' with present day storage battery equipment is so high that, in order to obtain requisite driving speeds without great waste of current through resistances,1t is necesparticularlyis thistrue by arranging all of and indicated by the numeral 5 may be of 95 I t e num'ber of revolutions per minute made 7 the speed reduction gearing on or at the rear nism6 to-be what is commonly called of the full floating type.

axle, as illustrated.

I have shown the rear drive axle mechathe axle tubes and "theirdriving' connection with the axle sections 15 mav be of any suitable type. I have illustrated each of the wheel hubs as mounted on anti-friction bearings 17, 18, and connected to the adjacent drive shaft section 15 by a clutch 19, the members of which are held in engagement in the well known manner by cap 20.

21 is a: gear casing extending forward from and secured to the enlarged portions 12 of the rear. axle housing. 22 is a tube or case interposed between the gear casing 21 and the motor casing 9. At the front end it is rigidly connected to the motor casing by bolts 23and at its rear end it is rigidly connected to the gear casing 21 by bolts 24.

The casing 21 is closed at its front end by a member or plate 21, which is held in place by the bolts 24. .At 21 this member 21 is formed with a suitable-opening through which a shaft 26 extends. The opening 21 is preferably of a size to provide'for a collar 21 and bearing sleeve 21 which known manner, as by bolts.

21, '21 indicate transverse supporting and strengthening webs arranged within the casing 21. These webs are spaced from each other and referably. formed integral with the circum erential walls of the casing. The

web21 is formed with upper and lower openings. v Around the former opemng and extending "from opposite faces of the web 21 are provided contiguous collars '21 the.

inner walls of .wliichformabearing for .an adjustable'sleeve 401 21 indicates an l'opening' -formed' in 'the I the web '21. The opening 21 is preferably formed with circumferential flanges 21", the inner walls of which form a'bearing and aline with the walls of the lower opemng in the web 21 to rotatably support eccentrically to the axle-of the shaft lower portion of 26--the opposite ends .of an, adjustable tube 31.

25 is a propeller shaft extending through the case. or tube 22 and suitably connecte at its front end by acoupling 25'- to the rear end of the. armature shaft 9" and at its rear end by a coupling 25 to the front end of the shaft 26.

close the space around the shaft'26 to keep. out the dust and foreign matter. The collar 21" may be detachably held in placein a well the adj ustmentsleeve e couplings 25 and 25 may, as indicated, be of a-type which cover pl ate4 5ldetachably secured to the caswill allow relatively longitudinal movement of the parts they connect as well as limited universal movement, to facilitate in assembly of the parts andto adapt the structure to simple and effective manu facturing standards. The shaft 26 is longitudinally disposed within the gear casing 21 and the adjustment tube 31. It is mounted at its rear end 1n a bearing 27 carried byand arranged at the rear end of the tube 31, and intermediate of its ends in a bear ing 28 mounted at the front end of said tube. This shaft 26 is held against longitudinal movement or thrusts by means of a collar-or annular boss 26 which engages with the bearing 27 on one side and a nut 27 on the 'screw threaded endof the shaft 26, which nut engages with the other side of said bearing 27. The bearing 27 is held against longitudinal movement within the sleeve or tube 31 by being pressed into engagement with theannul'ar shoulder 29 in said sleeve and there held by the screw threaded ring 30.. The bearing 28 is positioned in the'tube 31 by an annular boss 28", on the shaft 26 and a Washer 26. The bearings 27 and 28 are mounted in the tube 31 eccentric to the axis of the shaft 26 will be eccentric to the axis of the tube 31. To provide for the angular ad'ustlnentof the tube 31 there is arranged a out its periphery and near the middle of the tube a series each of whichmay be caused, by rotation of the tube 31, to register with a locking pin 34 carried by a plate 35 detachably seaxis thereof, so that the of openings 33 cured tothe .casing..21 so as'normally to cover the hand hole'36 through thecasing. When this cover 35 is removed the operator may place a tool or spanner in one or more of'the openings 33' in the adjustment tube 31 and turn the same as desired.

37 indicates 'a gear or sprocket suitably shaft and therein. At its rear end, the shaft 38 has secured to, or integrally formed with it, a bevel pinion 39 .which meshes with the bevel gear 14 of the differential mechanism. In-

' termediate of its ends'theshaft 38 is mountedin a hearing 38 which is arranged within 40. This bearing is shownto be one capable both of taking loads and endthrusts.

The rear end of the sleeve 40 is screw d threaded to :fit the screw threaded portion 42 in the webbrpartition, 21? which surrounds it. A Theex't'reme rear end of the sleeve 40 is notched or recessedat. 43 to receive the inner end of the locking 'pin 44, carried by the lei . the counter shaft 38. At its free end the shaft 38 is screw threaded to receive a nut- 50 and lock nut 51. These nuts hold the gear 49 in engagement with the inner bear was ing 21 so as to normally cover the hand opening 46 therethrough.

pressesagainst the front edge of the. race of the bearing. Y

49 indicates a gear or sprocket keyed in a well known manner to the front portion of ing member of the bearing 38, which mem; ber imturn is pressed against an annular shoulder 38 provided on the shaft38'. A silent chain 52 connects the gears or sprockets 37 and 49 for'power transmitting purposes. As clearly shown in the drawings, the gear 49 is larger than the gear 37 so that 'a reduction-in speed of the counters'haft 38 to the speed of the shaft 26 is efiected.

At its rear endthe casing 21 is secured to the front end of the enlarged section 12 of the rear axle housing as by means of bolts- 53. Adjacent to its rear end the casing 21 has an inwardly extending wall or flange 21 from which extends a bearing ring 21 arranged to receive'a bearing 54 for the extreme rear end of the countershaft'38. The flange 21 has a rearward extension 21 forming one section of a two part. hanger or support for the bearing 55 for one end of the differential mechanism, the other partof said bearing hanger or support being a strap or block 56 secured to the extension 2 1" by bolts 57. At the other side of the differat a point in advance of the motor.

ential mechanism 13 the casing 21 has a rearward extension 21 which forms with a strap or block 58 a support or hanger for and 21 may be detachably connected together, as by means of bolts, as illustrated.

The operation of the various parts will be rear wheels through the rear axle h'ousing,.

thence through the casing 21, tube 22, motor casing 9', ball 10, and cup 10 to the frame. The propelling force isapplied to the fiamfi ac of the side springs of the rear spring suspension. system is shackled at its front end to the frame and at its rear end to the transverse platform spring, so as to allow relative movement'of frame and springduring elastic deformations of the' spring. The rear .axle housing casing 21', tube 22, motor housing 9', and ball 10 move or swing as a uni tary structure relative to the frame; The

universal joint 10 is in'alinement with the 'axis of the armature shaft so asto permit the ball 10' and easing elements connected 'the rear wheels, as indicated. The torque.

action of. the rear axle housing, or its effort I therewith, including motor casing 9', tube to turn bodily in either directio about the I axis of the live shaft sections, under the infiuence of starting the rotation of the motor or of stopping the vehicle by applying-the brakes, is taken between the ball 10 and the cup 10, the casing elements interposed between the said ball and the rear axle housing serving as an entirety as a torque tube. Stay rods 60 pivoted at their front ends to the tube 22 and at their rear ends to the rear axle housing may be employed for strengthening -the structure and maintaining-desired relative position of parts.

By mounting thetmotor as herein shown and providing the speed reduction'gearing entirelyat the rear axle, an unusually quiet operating electric motor vehicle is obtained, since the so to speak sound board efi'ect noticeable in electric motor vehicles where the motor and reducing gear are arranged in close proximity to the body of the vehicle, is avoided.

' Lateral adjustment of the driven bevel gear14 to the driving pinion 39 may be efiected in any well known manner. Longitudinal adjustment of the bevel pinion 39 to the bevel gear 14: in order to insure quiet running of the gear may be cheated by turning the collar 40 in the desired direction. Adjustment of the silent chain 52, where such is employed, may be easily and readilv at the rear drive axle in the power transmisthe differential bearing 59. The parts -5 S sion line, i't will be understood that my invention so far as it relates to supporting a motor and connecting its housing with the rear axle housin is equally adaptable where but a single re notion is made at the rear axle, either by a single of bevel gears, a set of worm gears, or in any other well lmown manner.

I believe I am the first to support a motor from a motor vehicle fram'e'by means of a universal joint arranged in front of the motor and to have themotor housing directly connected to the housing of a rear drive axle so that they will move as a uni tary structure and wherein the parts are so correlated that the drive or propelling force for operating the motor vehicle will be transmitted to the frame entirely through said universal oint for supporting themo- -tor. I. also be ieve that I am the .first to support from a motor vehicle frame by a universal joint, an electric motor with its arn' rture shaft in line with said universal.

-joint,-the' casing of said motor being 'directly connected 'with the casing of a rear drive axle, so that'the axle and motor will swing as a unitary structure about said universal joint and also'about the axis of said armature shaft as a center.

It should be further noted that the construction is such that the desired relationship of the chain gearing and also of the final powertransmitting gears 39 and '14 may be adjusted when and while the casing 21 is detached from the rearaxle' housing. In otherwords, all of the speed reducing gear-in at the rear axle is sup ortd and carrie by the casing 21 and this structure as an entirety may e considered as a unitary one either for the purposes of assembly or of attachment to or detachment from the 4 rear axle housing, is being understood that the live axlesec'tions 15 may be withdrawn from or inserted into the differential mechanism at will without disturbing in any manner the differential mechanisms.

To those skilled in the art of making apparatus of the class described, many altera-- tions in construction and wide? differing embodiments and applications'o tion will suggest themselves, without de- I parting from the spirit andscope thereof.

1 and said rear axle housing, the said 1miversal joint being arranged in alinement with the armature shaft of said motor and supporting the motor from its front end, gearing connections between the rear end of said armature shaft and said difi'erential mechanism, a rigid support between the motor casing and said rear axle housing, whereby the motor casing and axle housing always swing together as a unitary structure, andconnections between the wheeled supports at the rear'end of said frame and said frame permitting free relative longitudinal move? ment of said frame and supports so that the propellingforce for the vehicle is trans mitted to the frame solelythrough the elements of said universal joint. ,2. In an electric motor vehicle, the 'combination with a vehicle frame and a real" drive axle for supporting same at its rear end, said rear axle havin a housing with live axle sections and liferential mechamsm incased thereby, of an electric motor my invenrigidly connected 'to and supported at its rear end by said housing-and having its armature shaft disposed longitudinally of said frame, gearing connections between the rear end of said armature shaft and said differential mechanism, a universal joint,

one element of said joint being connected with the motor and arranged in alinement with the armature shaft of the motor and entirely in front thereof and the other element of said joint being rigidly connected tosaid frame and connections between said rear axle housing and said frame permit tin free relative movement of said housing an frame so that the propelling force for the vehicle is, transnntted to the frame solely through the elements of said universal joint.

3. In a motor vehicle, the combination with a rear drive axle mechanism including a housing with live axle sections. and differential mechanism incased thereby, yielding supports interposed between said. housing and frame and connections between said frame and yielding supports permitting the free relative longitudinal movement of said frame and supports, ofa universal joint one element of WhlCll is rigidly secured to said frame in the vertical longitudinal plane of said differential mechanism, an electric motor arranged entirely between said universal joint and said rear axle mechanism, said motor being supported at its front end by the other element of said universal joint and having the axis of itsarmature shaft extending through said universal joint, a driving connection, betweenthe rear end of said armature shaft and said differential mechanism, and a rigid'connection between said motor and said rear axle housing, whereby the motor casing and rear axle housing always move together asa unitary structure and the propelling force for the vehicle is transmitted to the frame solely through the elements of said universal joint.

' 1 4. In an electric motor vehicle, the combination with a vehicle frame, a wheeled support for the frontend of said frame, and a wheeled support for the'rear end of said frame including a rear drive axle having a.

h using with live axle sections and a differen lal'mechanism incased thereby, of a universal joint one element of which is rigidly connected to said frame, an electric motor arranged entirely between said universal jointand said rear axle housing, said universal joint beingarranged in" alinement with the armature shaft of said motor .and

- having its, movable element supporting the motor from the front end thereof, gearing connections between the, rear end of the armature shaft of said motor and said differential mechanism, and a rigid support be tween the motor casingand said rear axle housing whereby the motor casing and axle structure.

nected with said frame to permit free rela-' tive longitudinal movement between said resilient supporting means and said frame, of an electric motor rigidly connected to and supported at its rear end bysaid rear axle housin and having its armature shaft disposed ngitudinally of said frame, gearin connections between the rear end of. sai

armature shaft and said differential mechanism and a universal joint, one element of whic supports said motor at its front end,

and the other element of which is rigidly connected to said frame so that the propelling force for the vehicle is transmitted to the frame solely .through the elements of said universal joint and said motor and rear axle always swing together relative to said frame as a unitary structure.

6; In a motor vehicle, the combination of a'frame, front and rear wheeled su ports therefor, a rear axle mechanism inclu ing a housing and a driven gear'mounted in said housing, a motor, a driven shaft, a propeller shaft between the shaft of said motor and said driven shaft for driving the latter, the motor shaft, propeller shaft and driven shaft being connected together in alinement, a counter shaft, reduction gearing between said counter shaft and said driven shaft, gearing between said counter shaft and said driven ear of said rear axle mechanism and means or swingably supporting the front end of said motor. v

7. In a motor vehicle, the combination of a frame, front and rear wheeled supports therefor, a rear axle mechanism including a housing and a driven gearlmounted in said housing, a motor, a driven shaft a propeller shaft between the shaft of said motor and said driven shaft for driving the latter, the motor shaft, propeller shaft and driven shaft being connected together in alinement,

a counter shaft, reduction gearing between said counter shaft and said driven shaft,

caring-between said counter shaft and said driven ear of said rear axle mechanism, means" or swingably supporting the front end of said motor, and a rigid connection between the rear end of said motor and said rear axle housing, whereby said motor and rear axle always swing together as a unitary structure. 7

8. In apparatus of the class described, the combination of rear drive axle mechanism leasing, a driven gear interpose including a housing, and a driven gear nections between said driven and counter.

shafts, and means for adjusting said driven shaft toward and from said counter shaft.

9. In apparatus of the class described, the combination of rear driveaxle mechanism including a housing and a driven gear mounted therein, a casing secured to said ,housing, a driven shaft n said casing, a

counter shaft mounted in bearin s in said casing, a driven gear interpose between said countershaft and said driven gear of said rear axle mechanism, chain gearing connections between said driven and counter shafts, means for adjusting said-driven shaft toward and from said counter shaft, and means for adjustin said counter shaft toward and from sai driven geaf'ofthe rear axle mechanism.

10. In apparatus of the class described, the combination of rear drive axle mechanism including a housing and-a driven gear mounted therein, a casin secured, to said housing, a driven shaft in said casing, a counter-shaft mounted in bearin s in said between said counter shaft and said driven gear of said rear axle mechanism, chain gearing connections between said driven and counter shaft, a sleeve mounted in said casing eccentric to said driven shaft, bearings within said sleeve for said driven shaft, and means for angularly adjusting said sleeve.

11. In apparatus of the class described, the combination of rear drive axle mechanism including a housing and a driven gear mounted therein, a casing secured to said housing, a driven shaft in said casing, a counter shaft mounted in bearings in said casing, a driven gear interposed between said counter shaft and said driven gear of said rear axle mechanism, chain caring connections between .said driven an counter shafts, a sleeve mounted in said casing eccentric to said driven shaft, bearings within said sleeve for said .dri'ven shaft, one of said bearings being arranged adjacent to the driving gear on said driven shaft and the other adjacent tothe free end of said driven shaft, and means for angularly adjusting said sleeve.

12. In apparatus of the class described, the combination of rear drive axle mechanism including a housing and a driven gear mounted therein, a casing secured to said housing, a driven shaft in said casing, bearings for said driven shaft arranged within said casing, an angularly adjustable support.

counter shaft mounted in said casing, chain nism, a counter shaft mounted within said casing and having at one end a driving gear meshing with said driven gear for said differential mechanism, chain reduction gearing between the other end of said counter shaft and said driven shaft, and means for adjusting said driven shaft relative to said counter shaft.

v 14. In apparatus of the class described, thecombination of a unitary structure comprising a casing, a driven shaft arranged in said casing, a counter shaft mounted in of the bearings I a tube mounted in the alined bearin said casing, bearing blocks extending beyond one end of said casing, a differential mechanism mounted in said bearing blocks, gearing interposed between said differential mechanism and said counter shaft, means for adjusting said driven shaft relative to said counter shaft, and a rear axle housing having an opening therein to receive said differential mechanism and driven gear connected therewith, said opening being closed by the adjacent end of said casing of said unitary structure. I v

15.In apparatus of the class described, the combination of a rear axle mechanism including a housing and a driven gear mounted therein, a casing having a pair of vertically disposed webs one of said webs having two bearings therein and the other web having a single bearing alined-with one i said first mentioned webf,

'- said two webs a driven shaft eccentricall mentioned web, chain reduction gearing be-t mountedwithin said tube, a counter sha t mounted in the other bearingin said-'first tween said driven and counter shafts, 'and ter shaft and said driven gear of'said rear axle mechanism. 7

- 16. In an electric motor vehicle, the combination with a vehicle frame, a wheeled vtial mechanism incased thereby, of an elecsupport for' the front end of said frame, and a wheeled support for the rear end of said frame including a drive axle having a housing with live axle sections and differentric motor having its armature shaft-arranged longitudinally of -isiaid' frame, gear-- a driving gear interposed between said coun-.

ing connections between said armature shaft of said armature shaft, and means rigidly g connecting said socket to said frame.

17 In an electric motor vehicle, the combination of a shaft drive axle includin a housing with live axle sections and a 'di erential mechanism incased thereby, an electric motor having its armature shaft disposed at right angles to said, axle sections, gearing connections between said armature shaft and differential mechanism including a propeller shaft means rigidly connecting whereby they always move together as a unitary structure, a ball carried by said connecting means co-axially with the armature shaft of said motor, a vehicle frame, resilient supports between said frame and said rear axle housing, and a socket for said ball rigidly secured to said frame.

18. In an electric motor vehicle, the combination with a vehicle frame, a wheeled support for the front end of said frame, and a wheeled support for the rear end of said frameincluding a drive axle having a housing with live axle sections and differential mechanism incased thereby, of'an electric motor having its armature shaft arranged longitudinally of saidframe, gearin connections between said armature sha t and said differential mechanism including aproswing together relatively to said frame'as a unitary structure, a ball and socket universal joint disposed co-axiall with the armature shaft of said motor an entirely at one end of said motor, the said ball being connected to move with said unitary structure about the axis of said armature shaft, and means rigidly connecting said socket to said frame.

19. In an electric motor vehicle, the combination with a vehicle frame, a wheeled.

support for the front end of said frame, and a wheeled port for'the rear end of said motor casing and axle housing together su said frame including a drive axle having a housing with live axle sectionsand different1al mechanism incased thereby, of an electric motor having its armature shaft arranged longitudinally of said frame, gearing connections between said armature shaft and said difierential mechanism including a propeller shaft, means connecting the motor casing and axle housing so that they will mechanism incased thereby, of an electric ma ma swing together relatively to said frame-as a unitary structure, a ball and socket universal joint disposed co-axially with the armature shaft of said motor and entirely at one end of said motor, the said ball being connected to move with said unitary structure about the axis of said armature shaft, and means for rigidly connecting said socket to said frame, the propelling force from said axle being transmitted to said frame through the said universal joint.

20. In an electric motor vehicle, the combination with a vehicle frame, a wheeled support for the front end of said frame, and a wheeled support for the rear end of said frame including a drive axle having a hous ing with live axle sections and differential motor having its armature shaft arranged longitudinally of said frame,'gearing connections between said armature shaft and said differential mechanism including a propeller shaft, means connecting the motor casing and axle housing so that they will swing together'relatively to said frame as'a unitarystructure, a ball and socket universal joint disposed co-axially' with the armature shaft of said motor and entirely at one end of said motor, the saidball being connected to move with saidunitary structureabout the axis, of said armature shaft, and means rigidly connecting said socket to said frame, torsional impulses on said rear'axle housing being counteracted between the elev ments of said universal joint.

21. In an electric motor vehicle, the combination-with a vehicle frame, a wheeled support for the front end of said frame, and

peller shaft, means connecting the motor casing and axle housing so that they will swing together relatively to said frame as a unitary structure, a ball and socket universal' joint disposed co-axially with the armature shaft of said motor and entirely at one end of said motor, the said ball be ing connected to move with said unitary structure about the axisof said armature shaft, and means rigidly connecting said socket to said frame, the propelling force.

from said axle to said frame being trans-- mitted through and the torsional -impulses on said axle housing being counteracted between, the elements of saiduniversal joint. In testimony whereof I aflix my signa ture, in the presence of two Witnesses EMIL GRUENFELITJT;

Witnesses I i S. M. MICKEY, I IRENE Hmmono.

said differential mechanism including a prov 

